The present invention relates to a source for a vacuum treatment process, in particular an arc or a combined arc and sputter source as well as a method for operating a source.
Arc sources as well as arc and sputter sources are applied in vacuum coating installations in various ways, with each source comprising different advantages according to the physical processes and the particular special technical implementations on which it is based.
In the following by arc source is understood a source in which on the surface of a target a light arc—also referred to in the literature as arc or spark—is ignited. Arc sources are especially suitable for processes in which high ionization of the metal vapor is of advantage. As an example is here listed the so-called ion plating method for the deposition of layers having especially high adhesiveness or the metal ion etching for the pretreatment and cleaning of surfaces.
By sputter source is understood in the following a source in which, with the aid of a plasma, material is sputtered off a target by ion bombardment. If, beyond that, with the aid of a suitably laid-out magnet system the plasma is concentrated substantially in the form of a closed ring in the proximity of the target, this is referred to as a magnetron sputter source.
For example sputter sources are highly suitable for the deposition of smooth layers, in particular if materials are to be transformed into the gas phase whose individual components have very different vapor pressures.
Within prior art a multiplicity of formations and special adaptations of highly diverse arc or sputter sources are known, which were developed to do justice to the broad requirement spectrum in different application fields.
For example German reference DE 19702928 C2 discloses an arc source, in which a magnet stabilizing the light arc is disposed in a cathode housing, which is sealed against the vacuum chamber and perpendicularly displaceable, and, in turn, is itself movable perpendicularly to the target surface.
Of disadvantage is therein the providing of vacuum sealing faces on parts moved against one another, which possibly are additionally subjected to strong temperature fluctuations through the operation of the arc source.
European reference EP 0459137 B1 discloses an arc and sputter source, in which a center-pole permanent magnet is disposed in fixed position on the back side of the target, while margin permanent magnets are supported axially displaceable relative to the target and center pole magnet. Thereby in a target-proximate position of the margin permanent magnets the operation as a sputter source is made possible, in a margin-distant position the operation as an arc source, in particular for pretreatment and cleaning by means of metal ion etching.
Based on the relatively complicated structure with axially displaceable magnet configurations, conventionally moved by electromotors, industrial implementations of such sources are in general large, structurally high and expensive of production.
European reference EP 0495447 B1 describes the principle of an arc source with which alloys of materials with very different vapor pressure can also be transformed into the gas phase without excessive spatter formation. However, with sources structured in this way, for example good target utilization cannot readily be attained or defined multilayer layers be deposited.